rsi: Fix some kernel-doc issues

The file header should not be kernel-doc.  Add missing 'rec_pkt'
description.  Update 'rsi_91x_init()'s parameter description.

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/rsi/rsi_91x_main.c:17: warning: Function parameter or member 'fmt' not described in 'pr_fmt'
 drivers/net/wireless/rsi/rsi_91x_main.c:156: warning: Function parameter or member 'rx_pkt' not described in 'rsi_read_pkt'
 drivers/net/wireless/rsi/rsi_91x_main.c:287: warning: Function parameter or member 'oper_mode' not described in 'rsi_91x_init'
 drivers/net/wireless/rsi/rsi_91x_main.c:287: warning: Excess function parameter 'void' description in 'rsi_91x_init'

Cc: Amitkumar Karwar <amitkarwar@gmail.com>
Cc: Siva Rebbagondla <siva8118@gmail.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200819072402.3085022-3-lee.jones@linaro.org